Which means that Comey was writing his memos with an eye to swaying future legal and public opinion. Upon finishing a memo, he would run it by his top deputies (see footnotes 187 and 188 in Volume II) to make sure it served its purpose. Comey’s memos may or may not be the “strong corroborating evidence” Mueller claims, but Comey surely intended for those memoranda to establish his version of events. For all his suspicions and speculations about the president’s intentions, oneformer FBI director demonstrates a remarkable lack of curiosity about the motives of another former FBI director.

Mueller clearly doesn’t just use footnotes for citations, but also for speculation and explanation and even a little what-iffery. Footnote 500 in Volume II, for instance, is a rather lengthy dissertation on a curious theory of how the president might have obstructed justice in firing Comey — a theory that imputes to Trump oracular foresight. We now know, thanks to Mueller’s inquiry, that there was not evidence to establish a Trump-Russia conspiracy. But the special counsel is unwilling to let go of the notion that Trump obstructed the investigation. Which leaves the special counsel team anticipating the obvious objection: How could the president have had a corrupt intent in firing Comey if there were no Russia conspiracy to cover up?

Mueller explains that Trump may have been afraid of what would get tangled in the net of a prosecutorial fishing expedition. “We considered whether the President’s intent in firing Comey was connected to other conduct that could come to light as a result of the FBI’s Russian-interference investigation,” footnote 500 states. “In particular, Michael Cohen was a potential subject of investigation because of his pursuit of the Trump Tower Moscow project and involvement in other activities. And facts uncovered in the Russia investigation, which our Office referred to the U.S. Attorney’s Office for the Southern District of New York, ultimately led to the conviction of Cohen in the Southern District of New York for campaign-finance offenses related to payments he said he made at the direction of the President.”

After all that fevered speculation – that when Trump fired Comey in May 2017 he might have been anticipating the raid on Cohen’s office in April 2018 — the footnote ends with a sheepish shrug: “The investigation, however, did not establish that when the President fired Comey, he was considering the possibility that the FBI’s investigation would uncover these payments or that the President’s intent in firing Comey was otherwise connected to a concern about these matters coming to light.”

What about the two FBI agents (one of them the ubiquitous Peter Strzok) who interviewed Flynn? The special counsel could have questioned them separately, asking each under oath whether they had told, suggested, hinted, or in any other way made Flynn to believe he was off the hook. In this case, the sources Mueller chooses not to question are more telling than the ones he does cite.

The footnote tells us just how thin the sourcing was for this fantastical scenario. And it tells us just how little in the way of plausible proof the Mueller team needed to go off on an investigative tangent. The special counsel even used one of his precious few written questions for the president (question V. a. to be exact) to ask whether Trump had been invited “to attend the World Chess Championship gala on November 10, 2016” and whether he had attended “any part of the event.” Trump responded that he had learned in “the course of preparing to respond to these questions” that early in 2016 the chess federation had inquired, fruitlessly, about using Trump Tower for the championship match. But in any case, Trump said in his written testimony that he “did not attend the event.”

As for the other days of the tournament, how plausible is it that Donald Trump just happened to pop over to the World Chess Championship? This is not just because Trump is more a WWE than a WCC sort of guy. Rather, it is a matter of common sense. Trump was the most famous person in the world, hated and loved and surrounded by unprecedented levels of security. Trump Tower, for example, was encircled by dump-trucks loaded with sand. And with such precautions being hastily imposed, Mueller entertains as a possibility worth inquiring into that the president-elect was able to slip away from his Trump Tower penthouse, travel some six miles to the South Street Seaport in lower Manhattan, take in some chess, schmooze with some Russians, and return to midtown — all without being seen?